fix(objc): Workaround for Swift/ObjC template issues (#1494)

This uses "non-standard" Swift annotations, but they've been supported
by the past few versions of Xcode and are in the process of being
standardized. Most importantly, they work for what we need.

Closes GH-1487.

templates/project/App/AppDelegate.h

@@ -19,10 +19,11 @@
 
 #import <Cordova/CDVAppDelegate.h>
 
-#warning It is unsafe to rely on the AppDelegate class as an extension point. \
-         Update your code to extend CDVAppDelegate instead -- \
-         This code will stop working in Cordova iOS 9!
+#ifndef __CORDOVA_SILENCE_HEADER_DEPRECATIONS
+    #warning It is unsafe to rely on the AppDelegate class as an extension point. \
+             Update your code to extend CDVAppDelegate instead -- \
+             This code will stop working in Cordova iOS 9!
+#endif
 
-@class AppDelegate;
-
-#import "App-Swift.h"
+@interface AppDelegate : CDVAppDelegate
+@end

templates/project/App/AppDelegate.swift

@@ -18,12 +18,11 @@
 */
 
 import UIKit
-import Cordova
 
 @main
-@objc // Remove compat hack in Cordova iOS 9
-class AppDelegate: CDVAppDelegate {
-    override func application(_ application: UIApplication, configurationForConnecting connectingSceneSession: UISceneSession, options: UIScene.ConnectionOptions) -> UISceneConfiguration {
+@_objcImplementation
+extension AppDelegate {
+    open override func application(_ application: UIApplication, configurationForConnecting connectingSceneSession: UISceneSession, options: UIScene.ConnectionOptions) -> UISceneConfiguration {
         return UISceneConfiguration(name: "Default Configuration", sessionRole: connectingSceneSession.role)
     }
 }

templates/project/App/Bridging-Header.h

@@ -18,3 +18,8 @@
  */
 
 #import <Cordova/Cordova.h>
+
+#define __CORDOVA_SILENCE_HEADER_DEPRECATIONS
+#import "AppDelegate.h"
+#import "MainViewController.h"
+#undef __CORDOVA_SILENCE_HEADER_DEPRECATIONS

templates/project/App/MainViewController.h

@@ -19,10 +19,11 @@
 
 #import <Cordova/CDVViewController.h>
 
-#warning It is unsafe to rely on the MainViewController class as an extension point. \
-         Update your code to extend CDVViewController instead -- \
-         This code will stop working in Cordova iOS 9!
+#ifndef __CORDOVA_SILENCE_HEADER_DEPRECATIONS
+    #warning It is unsafe to rely on the MainViewController class as an extension point. \
+             Update your code to extend CDVViewController instead -- \
+             This code will stop working in Cordova iOS 9!
+#endif
 
-@class MainViewController;
-
-#import "App-Swift.h"
+@interface MainViewController : CDVViewController
+@end

templates/project/App/ViewController.swift

@@ -19,7 +19,9 @@
 
 import Cordova
 
-@objc(MainViewController) // Remove compat hack in Cordova iOS 9
-class ViewController: CDVViewController {
+@_objcImplementation
+extension MainViewController {
 }
 
+class ViewController: MainViewController {
+}